Abstract
The aim of this work was to assess OchratoxinA (OTA) production of different Aspergillus carbonarius isolates, evaluate their growth profile through different growth measurements, and reveal any underlying correlation between them. Ten different isolates of A. carbonarius isolated from Greek vineyards located in different geographical regions were examined in vitro for their OTA production potential after an incubation period of up to 11 days. All fungal isolates grew on a synthetic grape juice medium (SGM) similar to grape composition at optimum conditions of temperature and water activity (25°C and 0.98 aw). Samples for OTA determination were removed at 3, 5, 7, 9, and 11 days of growth and analyzed by HPLC. Based on OTA measurements the isolates were characterized by diverse OTA production ranging from 50 to 2000 ppb at day 11. The different fungal growth responses (colony diameter, colony area, biomass, biomass dry weight, and colony density) have been measured and correlated with toxin production by means of principal components analysis (PCA), confirming satisfactory correlation and explained over 99% of data variability. Leudeking-Piret model was also used to study OTA production with time, revealing a mixed-growth associated trend and pointing a fail-safe model with slightly better prediction through colony area. This approach contributes to the assessment of correlation between mycotoxin production and different methods of fungal growth determination in relation to time.
Highlights
Ochratoxin A (OTA) is a widely detected mycotoxin that was first described as a wine contaminant by Zimmerli and Dick (1995)
A. carbonarius growth and OTA assessment food safety concern regarding the presence of OTA in foods and the European Union has established maximum OTA levels of 2 μg Kg−1 for wine, grape juice, grape nectar, and grape must intended for direct human consumption and 10 μg Kg−1 for direct dried wine fruits (European Commission, 2006)
Battilani et al (2001) pointed that the major source of OTA in grapes is the skin of berries and considering that grape juices, musts and wines are produced by pressing berries, the diffusion ability of OTA becomes evident (Valero et al, 2006a), making OTA contamination a problem originating in the field
Summary
Ochratoxin A (OTA) is a widely detected mycotoxin that was first described as a wine contaminant by Zimmerli and Dick (1995). OTA is known as a secondary metabolite produced by fungal species belonging to Aspergillus and Penicillium genera, that is related with nephrotoxic, hepatotoxic, genotoxic, teratogenic, and immunotoxic impact to humans and animals (IARC, 1993; Castegnaro et al, 1998). Fungal isolates identification around the Mediterranean and other parts of the world have shown the occurrence of OTA-producing Aspergillus species in grapes. There is strong evidence of the significance of A. carbonarius in OTA production since there is high incidence of ochratoxin-producing isolates within A. carbonarius spp. Battilani et al (2001) pointed that the major source of OTA in grapes is the skin of berries and considering that grape juices, musts and wines are produced by pressing berries, the diffusion ability of OTA becomes evident (Valero et al, 2006a), making OTA contamination a problem originating in the field. The lower the latitude the more frequent the occurrence and the grater the concentration of the toxin (Rosari et al, 2000; Pietri et al, 2001; Chiotta et al, 2013)
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